fix: GraphStructureReorganizer only optimizes the default cube tenant; periodic schedule never runs; cluster summary crashes on non-JSON LLM output #2480

Pre-submission checklist | 提交前检查

• I have searched existing issues and this hasn't been mentioned before | 我已搜索现有问题，确认此问题尚未提及
• I have read the project documentation and confirmed this issue doesn't already exist | 我已阅读项目文档并确认此问题尚未存在
• This issue is specific to MemOS and not a general software issue | 该问题是针对 MemOS 的，而不是一般软件问题

Bug Description | 问题描述

When MOS_ENABLE_REORGANIZE=true, the GraphStructureReorganizer periodic structure optimization silently works on only one graph tenant — the one configured on the shared default cube (memosdefault) — while data written through the REST API is stored under each request's user_name. As a result, no PARENT / INFERS / FOLLOWS edges are ever created for real tenant data, and the feature appears to "write nodes only, never build edges".

There are also two latent bugs in the same code path:

1. The 100-second periodic schedule never runs. GraphStructureReorganizer._periodic_optimize_structure registers schedule.every(100).seconds.do(self.optimize_structure, ...) but the loop never calls schedule.run_pending(), so these scheduled jobs are dead code. Only the _reorganize_needed new-node trigger actually executes (again, single-tenant).
2. _summarize_cluster crashes on non-JSON LLM output. If the LLM returns something that is not a JSON object, _parse_json_result yields a non-dict value and the subsequent response_json.get(...) raises, killing the whole optimization pass (including any already-computed sub-clusters).

Environment | 环境信息

• Version: main @ a7367d0 (2.0.33)
• Deployment: docker compose (docker/docker-compose.yml), MOS_ENABLE_REORGANIZE=true, NEO4J_BACKEND=neo4j-community

Root Cause | 原因分析

• src/memos/memories/textual/tree_text_memory/organize/reorganizer.py: _periodic_optimize_structure calls self.optimize_structure(scope=...) without a user_name, so it defaults to self.graph_store.config.user_name — the default cube's tenant (memosdefault), not the tenants that actually received writes via /product/add.
• The same method registers schedule.every(100).seconds.do(...) jobs but its polling loop lacks schedule.run_pending().
• _summarize_cluster assumes the LLM always returns a parseable JSON object and passes the result straight into _create_parent_node, so a single malformed response aborts the entire pass.

Proposed Fix | 建议修复

I have a working patch (validated on a live deployment) that:

1. Adds Neo4jGraphDB.get_all_user_names() (src/memos/graph_dbs/neo4j.py) — MATCH (n:Memory) RETURN DISTINCT n.user_name, with graceful fallback to the configured user_name.
2. Adds GraphStructureReorganizer._optimize_all_users(scope) — enumerates all tenants in the graph and runs optimize_structure(scope=..., user_name=...) for each, tolerating per-tenant failures.
3. Routes both the scheduled jobs and the _reorganize_needed trigger through _optimize_all_users, and adds the missing schedule.run_pending() call.
4. Makes _summarize_cluster return None when the LLM response is not a JSON object, and guards _create_parent_node / add_edge calls against None.

Note: since BaseGraphDB defines the interface, other graph backends (neo4j-community / polardb / postgres) would need an equivalent get_all_user_names() implementation — or the base class could provide a default fallback to config.user_name.

I am not submitting a PR yet per my own workflow, but I can if the approach is endorsed.

Willingness to Implement | 实现意愿

• I'm willing to implement this myself | 我愿意自己解决